Edentulism refers to a state of full or partial lack of teeth. This situation may interfere with essential functions such as mastication, speech and even appearance.

Dental implants inserted to the mandible or maxilla is a common treatment modality aiming to restore edentulus alveolar ridges by providing support and anchorage for removable or fixed dental prosthesis.There are cases which in addition to a lack of teeth suffer from lack of sufficient bone tissue volume to support the dental implant.A situation like this may originate from a variety of reasons such as residual bone atrophy, prior alveolar bone destruction due to periodontal disease and even a traumatic tooth extraction. In such cases, a routine alveolar bone augmentation is done to enable a dental implant installation at this site.Guided bone regeneration (GBR) is a widely used technique used to augment edentulus bone ridges. It relies on an inert membrane covering a bone substitute placed over the bony site requiring augmentation. The bone substitute provides a scaffold to alveolar regeneration by the host's osteoblasts while the membrane prevents unwanted epithelial cells to migrate to the bony defect area.

The investigators research is a aimed to preform a follow up after patients who already went through a GBR procedure and before inserting a dental implant. Patients answering the inclusion but not the exclusion criteria will go through an alveolar computerized tomography (C.T) done routinely before inserting dental implants.At the day of Dental implantation - residual bone left from the site of implantation (after preparing the site with a trephine bur) will be taken to a histological analysis. The results from the C.T and the histological examination will be analyzed for bone quantity (volume) and quality and will allow a comparison of bone characteristics obtained by using different routinely used bone substitutes.

Inclusion Criteria:

1. Healthy men and women over 18 years of age, eligible for signing
2. Patients who went through a GBR procedure previous to an insertion of a dental implant which hasn't been inserted yet
3. Patients who understand the meaning of the treatment (routine dental implant insertion) and the follow up study, and approves participation in booth of them

Exclusion Criteria:

1. Pregnant or nursing women. children or non judgemental patients
2. Patients with uncontrolled diabetas mellitus, rheumatoid arthritis or osteoporosis.
3. Patients with a pathology present near the site of dental implantation

Healty over 18 years of age Patients who went through a GBR procedure previous to an insertion of a dental implant which hasn't been insertd yet